I had originally crafted a bent oval-shaped sheet of 0.024" alclad to serve as a shiny surface to rest inside the wingtip light well, and the AeroLED wingtip lights would sit on this. However, I decided to get MUCH fancier and use sheets of mirrored acrylic which I found on the Amazon Aviation Supply website.
From the 1' x 2' x 1/4" sheet, I cut half-oval plates using the original alclad pieces as templates. I used my hand cutter to cut, and the band saw to shape and bevel. The mirror's top side was covered with a sheet of protective plastic, but the mirror side was not protected so I had to be really careful.
I had already drilled 3 screw holes into each face of the wingtip light recess, so I used those to backdrill screw holes through the mirror pieces once they were shaped to fit in place under the clear cover.
Marking the acrylic
Cutting and shaping
Match-drilling through the wingtip into the mirror piece